New(ish) feature: enable/disable individual initiator sessions in a multi-session application

[gbirchmeier]

Inspired by #945, which proposes a fix to a feature that we don't intentionally have.

However, making that accidental feature official won't take very much work, so I'm going to go ahead and do it.

I'm going to add Session.Enable/Disable with proper doc comments, and internal-ize Session.Logon/Session.Logout which shouldn't be public.

The fix that @petrmosna15 proposed will be baked into these new functions.

(close #945)

[gbirchmeier]

@petrmosna15 & @mgottvald -

I thought this was going to be an easy one, but it's not. This logic is weirder than I expected.

The variable _lastConnectTimeDt isn't per-session, but is shared for ALL sessions controlled by the Initiator. (This logic is in SocketInitiator.OnStart()). Or, more accurately, that isn't applying to any session, but to the SocketInitiator itself running the Connect procedure (which covers all sessions). To be honest, I'm not crystal clear on the "why" of all the lines that I'm reading.

I need to write a demo app and try a few things and make sure I know what is going on here before I start hacking code.

[petrmosna15]

Yes, you are correct — changing the Initiator would affect all sessions. On the other hand, for the other sessions, it would only mean that they would attempt to connect if not already connected, right?